Stabilized chlorinated hydrocarbon



United States Patent STABILIZED CHLORINATED HYDROCARBON Andr Ryckaert and Julien Mulders, Brussels, Belgium,

assignors to Solvay & Cie, Brussels, Belgium, a corporation of Belgium No Drawing. Filed Jan. 15, 1969, Ser. No. 791,486

Claims priority, applicastionsgelgium, Jan. 17, 1968,

9 The portion of the term of the patent subsequent to Nov. 18, 1986, has been disclaimed Int. Cl. C07c 17/40, 17/42 U.S. Cl. 260-6525 6 Claims ABSTRACT OF THE DISCLOSURE The stabilized chlorinated hydrocarbon contains both a diaziridine compound and a base having a pyrrole nucleus.

BACKGROUND OF THE INVENTION This invention relates to a process for stabilizing chlorinated hydrocarbons and to the stabilized chlorinated hydrocarbon composition. More particularly, the present invention is directed to an improvement over the process for stabilizing chlorinated hydrocarbons described in Canadian Pat. No. 792,807 which issued onAug. 20, 1968 which corresponds to U.S. patent application Ser. No. 676,620, filed Oct. 19, 1967, now Pat. No. 3,479,414, and which is assigned to Solvay et Cie.

According to the above patent, it is possible to prevent the decomposition of chlorinated hydrocarbons, particularly trichloroethylene and perchloroethylene, during storage and while in use, by adding, as a stabilizer, a diaziridine (diazacyclopropane) of the formula:

or an alkyl derivative thereof, such as 1,2-diethyl diaziridine. It is specified in the patent, that combinations of the above compounds may be used as stabilizers; similarly, diaziridine or its alkyl derivatives may be used with other known stabilizing agents.

In U.S. Pat. No. 2,492,048 issued on Dec. 20, 1949 to Walter Klabunder there is a description of the use of N- alkyl derivatives of pyrrole, for example, N-methylpyrrole or N-ethylpyrrole, for stabilizing trichloroethylene; the stabilizing amounts should be comprised between 0.001 and 1% by weight.

SUMMARY OF THE INVENTION It has now been found that in the stabilization of chlorinated hydrocarbons, an outstanding synergistic effect is obtained by using a mixture of diaziridine or an alkyl derivative thereof, and a base having a pyrrole nucleus.

The present invention is directed to a process for stabilizing chlorinated hydrocarbons by the addition of N- heterocyclic compounds selected from the group consisting of diaziridine and/ or alkyl derivatives thereof, according to U.S. patent application No. 676,620, now Pat. No. 3,479,414, in which there is used simultaneously a co-stabilizer having a synergistic effect, comprising one or more bases having a pyrrole nucleus, such as pyrrole or the N- alkyl derivatives. The present invention is also directed to stabilized chlorinated hydrocarbon containing both of these stabilizing compounds.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The stabilizing amounts of diaziridine or the alkyl derivatives thereof and of the bases having a pyrrole nucleus "ice are each preferably comprised between 0.025 and 0.5 gper liter of chlorinated hydrocarbon.

Other known stabilizers may, of course, be added to the above mixtures.

It has been found most preferable ot use diaziridine and/or N,N-dialkyldiaziridine in which the alkyl groups contain 1 to 3 carbon atoms. The combination of the aforementioned diaziridine compound and pyrrole and/ or N-alkylpyrrole, most preferably wherein the alkyl group contains 1 to 3 carbon atoms yields a chlorinated hydrocarbon composition of exceptional stability.

The synergistic effect of the two types of co-stabilizers in accordance with the present invention has been established by the global test which has been described in detail in U.S. patent application No. 676,620. However, due to the fact that each compound in the present synergistic combination has a large intrinsic efliciency even when used alone, for the present case, a more active light source was used in order to increase the strength of the test. For this purpose, there was used a Philips blue actinic TL 5 lamp, instead of the TL 10 as in the test described in U.S. patent application No. 676,620.

The following table shows the results which have been obtained by applying the modified global test to trichloroethylene to which has been added the stabilizer(s) in amounts of mg. per liter of trichloroethylene;

Duration resistance,

It can be seen from this table that the mixtures of the two types of co-stabilizers give results which are substantially higher than the sum of the individual effects of each stabilizer.

The invention is not limited to the above specific examples with respect to the nature of the co-stabilizers and the amounts utilized. Similarly, the invention may be used not only for the stabilization of trichloroethylene, but also for the stabilization of perchloroethylene, carbon tetrachloride, dichloroethanes, trichloroethanes and other analogous chlorinated solvents, as well as mixtures of such solvents.

As stated above, a plurality of stabilizers of the diaziridine group and/or of the group comprising bases having pyrrole nucleus may be used. Furthermore, other stabilizers which are well known may be used simultaneously as those according to the present invention.

What we claim and desire to secure by Letters Patent is:

1. Stabilized chlorinated hydrocarbon composition wherein said chlorinated hydrocarbon is selected from the group consisting of perchloroethylene, trichloroethylene, carbon tetrachloride, a dichloroethane, a trichloroethane and mixtures thereof containing a heterocyclic compound selected from the group consisting of diaziridine, a lower alkyl diaziridine and mixtures thereof in a stabilizing amount of about 0.025 to 0.5 g. per liter of said chlorinated hydrocarbon, and a base selected from the group consisting of pyrrole, and N-alkylpyrrole wherein the alkyl group contains 1 to 3 carbon atoms in a stabilizing amount of about 0.025 to 5 g. per liter of said chlorinated hydrocarbon.

2. Stabilized chlorinated hydrocarbon according to claim 1 containing a synergistic stabilizing composition consisting of at least one compound selected from the group consisting of diaziridine and N,N-dialkyldiaziridine 4 wherein the alkyl group contains 1 to 3 carbon atoms and 3,269,953 8/1966 Boothman 260652.5 at least one compound selected from the group consisting 3,314,892 4/1967 Graham II 260652.5X of pyrrole and N-alkylpyrrole wherein the alkyl group 3,328,474 6/1967 Blankenship 260-6525 contains 1 to 3 carbon atoms. 3,397,246 8/ 1968 Ryckaert et a1 260652.5 3. Stabilized chlorinated hydrocarbon according to 3,452,107 6/1969 Archer et a1 260652.5 claim 1 wherein said chlorinated hydrocarbon is perchloa roethylene. References Cited 14. siabiltilzed chlogingted hydirtfcagirbon bacco rdinghlto UNITED STATES PATENTS i i g g C mate 1y mar onls mc 1,372,363 8/1964 France 260-6525 References cted HOWARD T. MARS, Primary Examiner UNITED STATES PATENTS 2,492,048 12/1949 Klabunde 260652.5

2,803,676 8/1957 Willis 260 652.5 r -52171,401,405

2,973,392 2/1961 Graham 2606S2.5 

